Semiconductor device and method for forming the same

Abstract

A semiconductor and a method for forming the same are disclosed. The method for forming the semiconductor device includes forming a buried gate on a semiconductor substrate including an active region, forming an insulating layer on the semiconductor substrate, selectively removing the insulating layer from at least an upper part of the active region, forming a bit line on an upper part between the buried gates formed on the active region, and forming a storage electrode contact that is formed at both sides of the bit line and has an extended lower part, so that prevents short circuiting between the storage electrode contact and the bit line, and improves contact resistance by enlarging a contact area between the storage electrode contact and the active region, so that unique characteristics of the semiconductor device are improved.

1. A method for forming a semiconductor device comprising:
 forming neighboring buried gates on a semiconductor substrate including an active region; 
 forming an insulating layer on the semiconductor substrate; 
 selectively removing the insulating layer from at least a region over an upper part of the active region; 
 forming a photoresist pattern to expose a cell area using an exposure mask for opening the cell area of the semiconductor substrate; 
 etching the insulating layer using the photoresist pattern as an etch mask; 
 forming a bit line on the upper part of the active region between the neighboring buried gates; and 
 forming a storage electrode contact plug that is adjacent to the bit line and that has a laterally extending lower portion, 
 wherein forming the bit line includes: 
 forming a first interlayer insulating layer and a bit line contact plug on the active region between the neighboring buried gates; 
 forming a bit line electrode, a first nitride layer, and a hard mask layer on the first interlayer insulating layer, the bit line electrode contacting the bit line contact plug; 
 etching the hard mask layer, the first nitride layer, the bit line electrode, and the insulating layer to form a bit line structure; and 
 forming a bit line spacer on a sidewall of the bit line structure. 
 
     
     
       2. The method according to  claim 1 , further comprising:
 after forming the photoresist pattern, performing a planarization etching process on the insulating layer exposed by the photoresist pattern. 
 
     
     
       3. The method according to  claim 1 , wherein forming the buried gate includes:
 forming a buried gate reserved area in the semiconductor substrate; 
 providing a conductive material for a gate in the buried gate reserved area, and performing an etch-back process on the conductive material; 
 forming a capping nitride layer over the etched-back conductive material. 
 
     
     
       4. The method according to  claim 1 , wherein forming the bit line contact plug includes:
 forming the first interlayer insulating layer on the semiconductor substrate; 
 forming a photoresist pattern for defining a bit line contact hole on the first interlayer insulating layer; 
 etching the first interlayer insulating layer using the photoresist pattern as an etch mask so as to expose the semiconductor substrate; and 
 forming a conductive material for the bit line contact plug over an entire surface of the semiconductor substrate, and performing a planarization etch process on the conductive material so as to expose the first interlayer insulating layer. 
 
     
     
       5. The method according to  claim 1 , wherein forming the storage electrode contact plug includes:
 forming a second interlayer insulating layer over the semiconductor substrate including the bit line structure; 
 forming a photoresist pattern for defining a storage electrode contact hole on the second interlayer insulating layer; 
 forming the storage electrode contact hole by etching a portion of the second interlayer insulating layer formed at both sidewalls of the bit line using the photoresist pattern as an etch mask to expose the semiconductor substrate; 
 enlarging a lower portion of the storage electrode contact hole so that the lower portion of the storage electrode contact hole is wider than an upper portion of the storage electrode contact hole; and 
 providing a conductive material in the storage electrode contact hole. 
 
     
     
       6. The method according to  claim 5 , wherein the enlarging step includes a wet etch process or a dry etch process. 
     
     
       7. A method for forming a semiconductor device comprising:
 forming neighboring buried gates on a semiconductor substrate including an active region; 
 forming an insulating layer on the semiconductor substrate; 
 selectively removing the insulating layer from at least a region over an upper part of the active region; 
 forming a bit line on the upper part of the active region between the neighboring buried gates; and 
 forming a storage electrode contact plug that is adjacent to the bit line and that has a laterally extending lower portion, 
 wherein selectively removing the insulating layer includes: 
 forming a photoresist pattern to expose at least the region over the upper part of the active region on the insulating layer; and 
 etching the insulating layer using the photoresist pattern as an etch mask, and 
 wherein forming the bit line includes: 
 forming a first interlayer insulating layer and a bit line contact plug on the active region between the neighboring buried gates; 
 forming a bit line electrode, a first nitride layer, and a hard mask layer on the first interlayer insulating layer, the bit line electrode contacting the bit line contact plug; 
 etching the hard mask layer, the first nitride layer, and the bit line electrode to form a bit line structure; and 
 forming a bit line spacer on a sidewall of the bit line structure. 
 
     
     
       8. The method according to  claim 7 , wherein forming the bit line contact plug includes:
 forming a first interlayer insulating layer over the semiconductor substrate; 
 forming a photoresist pattern for defining the bit line contact hole on the first interlayer insulating layer; 
 etching the first interlayer insulating layer using the photoresist pattern as an etch mask so as to expose the semiconductor substrate; and 
 forming a conductive material for the bit line contact plug over an entire surface of the semiconductor substrate, and performing a planarization etch process on the conductive material so as to expose the first interlayer insulating layer. 
 
     
     
       9. The method according to  claim 7 , wherein forming the storage electrode contact plug includes:
 forming a silicon nitride layer on the insulating layer including the bit line; 
 forming a second interlayer insulating layer on the silicon nitride layer; 
 forming a photoresist pattern defining a storage electrode contact hole on the second interlayer insulating layer; 
 forming a first storage electrode contact hole using the photoresist pattern as an etch mask and using the silicon nitride layer as an etch stop layer; 
 etching the etch stop layer; 
 etching the first interlayer insulating layer using the first storage electrode contact hole as an etch mask, and thus forming a second storage electrode contact hole; 
 enlarging a lower portion of the second storage electrode contact hole so that the lower portion of the second storage electrode contact hole is wider than an upper portion of the second storage electrode contact hole; 
 providing a conductive material within the first storage electrode contact hole and the second storage electrode hole. 
 
     
     
       10. The method according to  claim 9 , wherein the enlarging step includes a wet etch process or a dry etch process. 
     
     
       11. The method according to  claim 7 , wherein forming the neighboring buried gates includes:
 forming a buried gate reserved area in the semiconductor substrate; 
 providing a conductive material for a gate in the buried gate reserved area, and performing an etch-back process on the conductive material; and 
 forming a capping nitride layer over the etched-back conductive material. 
 
     
     
       12. A method for forming a semiconductor device comprising:
 forming neighboring buried gates on a semiconductor substrate including an active region; 
 forming an insulating layer on the semiconductor substrate; 
 selectively removing the insulating layer from at least a region over an upper part of the active region; 
 forming a bit line on the upper part of the active region between the neighboring buried gates; and 
 forming a storage electrode contact plug that is adjacent to the bit line and that has a laterally extending lower portion, 
 wherein selectively removing the insulating layer includes: 
 forming a photoresist pattern on the insulating layer using an exposure mask that includes a shielding pattern having a width smaller than that of the buried gate; and 
 etching the insulating layer using the photoresist pattern as an etch mask, and 
 wherein forming the bit line includes: 
 forming a first interlayer insulating layer and a bit line contact plug on the active region between the neighboring buried gates; 
 forming a bit line electrode, a first nitride layer, and a hard mask layer on the first interlayer insulating layer, the bit line electrode contacting the bit line contact plug; 
 etching the hard mask layer, the first nitride layer and the bit line electrode to form a bit line structure; and 
 forming a bit line spacer on a sidewall of the bit line structure. 
 
     
     
       13. The method according to  claim 12 , wherein forming the bit line contact plug includes:
 forming a first interlayer insulating layer on the semiconductor substrate; 
 forming a photoresist pattern for defining a bit line contact hole on the first interlayer insulating layer; 
 etching the first interlayer insulating layer using the photoresist pattern as an etch mask so as to expose the semiconductor substrate; and 
 forming a conductive material for the bit line contact plug on an entire surface of the semiconductor substrate, and performing a planarization etch process on the conductive material so as to expose the first interlayer insulating layer. 
 
     
     
       14. The method according to  claim 12 , wherein forming the storage electrode contact plug includes:
 forming a silicon nitride layer on the insulating layer including the bit line; 
 forming a second interlayer insulating layer on the silicon nitride layer; 
 forming a photoresist pattern defining a storage electrode contact hole on the second interlayer insulating layer; 
 forming a first storage electrode contact hole using the photoresist pattern as an etch mask and using the silicon nitride layer as an etch stop layer; 
 etching the etch stop layer; 
 etching the first interlayer insulating layer using the first storage electrode contact hole as an etch mask, and thus forming a second storage electrode contact hole; 
 enlarging a lower portion of the second storage electrode contact hole so that the lower portion of the second storage electrode contact hole is wider than an upper portion of the second storage electrode contact hole; 
 providing a conductive material in the first storage electrode contact hole and the second storage electrode hole. 
 
     
     
       15. The method according to  claim 14 , wherein the enlarging step includes a wet etch process or a dry etch process. 
     
     
       16. The method according to  claim 12 , wherein forming the neighboring buried gates includes:
 forming a buried gate reserved area in the semiconductor substrate; 
 providing a conductive material for a gate in the buried gate reserved area, and performing an etch-back process on the conductive material; and 
 forming a capping nitride layer over the etched-back conductive material. 
 
     
     
       17. A semiconductor device comprising:
 neighboring buried gates in a semiconductor substrate including an active region; 
 an insulating layer formed on the buried gate; 
 a bit line formed on an upper part of the active region between neighboring buried gates; and 
 a storage electrode contact plug that is formed at both sides of the bit line, the storage electrode contact plug having a lower portion that is wider than an upper portion, 
 wherein the bit line includes a bit line contact formed on the active region between the neighboring buried gates, a first interlayer insulating layer pattern formed at sidewalls of the bit line contact, a laminated structure including a bit line electrode, a first nitride layer, and a hard mask layer, the laminated structure being provided on the bit line contact plug and the first interlayer insulating pattern, and a bit line spacer formed on sidewalls of the laminated structure, 
 wherein the buried gate includes a gate electrode that is buried in a lower part of a buried gate reserved area in the semiconductor substrate, and a capping nitride layer that is formed over the gate electrode and is buried in the buried gate reserved area, and 
 wherein the insulating layer is formed on the capping nitride layer and is buried in the buried gate reserved area. 
 
     
     
       18. The semiconductor device according to  claim 17 , wherein the bit line includes
 a bit line spacer formed on a sidewalls of the laminated structure and the first interlayer insulating layer pattern. 
 
     
     
       19. The semiconductor device according to  claim 17 , wherein the insulating layer is formed on the capping nitride layer and is narrower than the buried gate. 
     
     
       20. The semiconductor device according to  claim 17 , further comprising:
 a storage electrode contact plug spacer formed on a sidewall of the bit line spacer.